A high level modeling system (HLMS) is a software tool in which electronic designs can be described, simulated, and translated by machine into a design realization. An HLMS provides a higher level of abstraction for describing and simulating an electronic circuit than does a hardware description language (HDL) simulation environment such as the ModelSim environment from the Model Technology company. An HLMS generally provides a mathematical representation of signals as compared to standard logic vectors in a hardware description language (HDL). It is desirable for the high-level abstractions to be precisely correlated with the ultimate implementation representation, both in simulation semantics and in implementation. The Xilinx System Generator tool for DSP and the MathWorks' Simulink and MATLAB environments are example HLMS's in which such capabilities are desirable.
In an HLMS-based design, there may be some components external to the HLMS environment that under certain circumstances, are desirable to have controlled by and involved in HLMS simulations. For example, it is sometimes useful to take existing HDL components that have been designed using a tool separate from the HLMS and incorporate the HDL components into an HLMS simulation environment. Furthermore, there may be existing hardware components that are desirable to involve in the HLMS simulation. The process of incorporating one or more external components into an HLMS-based simulation may be referred to as HLMS co-simulation.
A variety of different co-simulation engines are available for use in co-simulating part of a design. The particular co-simulation engine that is selected for use in the simulation depends on design objectives as well as the compatibility between the HLMS and various co-simulation engines.
Example co-simulation engines include both software-based and hardware-based systems. The Modelsim simulator and the NC-SIM simulator from Cadence are example software-based simulators, and the Wildcard development board from Annapolis Microsystems and the Benone development board from Nallatech are example hardware platforms that can be co-simulated in an HLMS environment. In software-based co-simulations the user may perform a behavioral simulation or perform simulation using a synthesized and mapped version of the design.
A hardware-based co-simulation engine based, for example, on a reconfigurable hardware platform that includes a field programmable gate array (FPGA), often includes a sophisticated interface for connecting and communicating with an off-board system that can control the hardware-based co-simulation engine. An example off-board system is a host PC running the simulation software. Example interfaces such as PCI, USB or Ethernet are often used. Even though these interfaces are common, a suitable logic core for implementing the interface on the device may be a burden to obtain and non-trivial to create from scratch. This may present a substantial barrier for a designer seeking to exploit the advantages of co-simulation.